When an egg is stored in its raw state, the yolk of the egg rises within the interior of the egg. Thus, there is only a thin layer of egg white between the yolk and the egg shell. In extreme cases, the egg yolk completely displaces the egg white and abuts against the egg shell. If an egg is cooked with the yolk in this position and subsequently peeled, the relatively thin or non-existent layer of egg white is very often damaged, especially when eggs are peeled by machine. Often times, the egg yolk falls out of the cooked egg, whereby the egg is unusable. Losses resulting from damaged egg whites and lost yolks are very high when eggs are processed commercially.
A number of attempts have been made to center the yolk of the egg, i.e. to bring the egg yolk into a position where it is enclosed on all sides by a thick layer of egg white. Centering results when the egg yolk lies concentrically relative to the longitudinal axis of the egg and is spaced from the ends of the egg along the longitudinal axis so that the thickness of the layer of egg white between the end of the egg lying closest to the yolk corresponds roughly to the thickness of the egg white layer enclosing the egg yolk.
Eggs are normally stored with their longitudinal axes running vertically with the pointed end of the egg directed downwardly. Consequently, when an egg is stored for a long period of time, the egg yolk travels upwardly in the direction of the longitudinal axis toward the rounded end of the egg.